Pyrolysis of polyurethane compound-containing material in order to recover raw materials

Abstract

The invention relates to a process according to claim 1 and pyrolysis devices used therein for the pyrolysis of pyrolysis stock comprising polyurethane-containing material, allowing carrying out pyrolysis on an industrial scale. According to the invention, even with higher amounts of pyrolysis stock an amount of pyrolysis product is obtained that contains cleavage products which can be reused for the synthesis of polyurethane-containing material.

1 . A pyrolysis process, comprising:
 (a) introducing a pyrolysis feedstock comprising:
 i) a material comprising at least one polymeric compound having at least one polyurethane structural unit of the formula (I), 
   
       
         
           
           
               
               
           
         
         
           
             where 
             Q is a hydrocarbon radical having 8 to 70 carbon atoms, and 
             n is a number having a value of 2 to 10, 
             and —* denotes a covalent bond to the polymer backbone, 
           
           and 
           ii) at least one catalyst influencing thermal degradation of said polymeric compound, into a reactor; 
         
         (b) degradation at least of the material of the pyrolysis feedstock introduced in step (a) in the reactor at a temperature of 250° C. to 700° C. to obtain a gas-phase product as pyrolysate and a non-gas-phase pyrolysis residue, wherein
 (i) during said degradation, the amount of oxygen gas in the reactor is not more than 2.0% by volume based on the total volume of the gases present in the reactor, and 
 (ii) during said degradation, the pyrolysate is discharged from the reactor, and 
 (iii) said pyrolysis residue is discharged from the reactor; 
 
         (c) cooling the discharged pyrolysate to a temperature of less than 250° C. to obtain a pyrolysis product selected from pyrolysate condensate, pyrolysate sublimate or a mixture thereof; and 
         (d) optionally working up the pyrolysis product. 
       
     
     
         2 . The process as claimed in  claim 1 , wherein the temperature in step (b) is from 300° C. to 700° C. 
     
     
         3 . The process as claimed in  claim 1 , wherein the absolute pressure in step (b) is not more than 1.2 bar. 
     
     
         4 . The process as claimed in  claim 1 , wherein the introduced pyrolysis feedstock is temperature-controlled at a target temperature of 250° C. to 700° C. and that, on reaching the target temperature, the residence time of the temperature-controlled pyrolysis feedstock until the time of discharge of the pyrolysis residue resulting therefrom is from 1 second to 5 hours. 
     
     
         5 . The process as claimed in  claim 1 , wherein the step of discharging the pyrolysate from the reactor comprises (i) passing a gas stream through the reactor or (ii) suction. 
     
     
         6 . The process as claimed in  claim 1 , wherein the step of discharging the pyrolysate from the reactor comprises passing a gas stream through the reactor, the flow rate of which in the reactor, as the superficial velocity, is from 0.01 m/s to 20 m/s. 
     
     
         7 . The process as claimed in  claim 1 , wherein at least steps (a) and (b) run concomitantly in the context of continuous process control. 
     
     
         8 . The process as claimed in  claim 1 , wherein the amount of oxygen gas in the reactor in step (b) is not more than 0.5% by volume, based on the total volume of the gases present in the reactor. 
     
     
         9 . The process as claimed in  claim 1 , wherein an inert gas is passed through the reactor packed with said material. 
     
     
         10 . The process as claimed in  claim 1 , wherein the polymeric compound contains at least one polyurethane structural unit of the formula (Ia) 
       
         
           
           
               
               
           
         
         where 
         n is a number having a value of 0 to 8, and —* denotes a covalent bond to the polymer backbone. 
       
     
     
         11 . The process as claimed in  claim 1 , wherein the polymeric compound is obtained by reaction at least of
 i1) at least one organic isocyanate compound containing two to ten isocyanate groups attached to a hydrocarbon unit having 8 to 70 carbon atoms; with   i2) at least one organic compound having at least two hydroxy groups.   
     
     
         12 . The process as claimed in  claim 11 , wherein the at least one organic isocyanate compound contains, as said hydrocarbon unit, a unit that is derived from aliphatic hydrocarbon units, cycloaliphatic hydrocarbon units, araliphatic hydrocarbon units, aromatic hydrocarbon units or heterocyclic hydrocarbon units. 
     
     
         13 . The process as claimed in  claim 11 , wherein the at least one organic isocyanate component comprises at least one polyphenylpolymethylene polyisocyanate of the formula (III), 
       
         
           
           
               
               
           
         
       
       where n is a number having a value of 0 to 8. 
     
     
         14 . The process as claimed in  claim 1 , wherein said material is introduced into the reactor in the form of solid particles. 
     
     
         15 . The process as claimed in  claim 1 , wherein the catalyst comprises at least one compound from the group consisting of inorganic salts, minerals, metal oxides, mixed oxides, clays, and zeolites. 
     
     
         16 . The process as claimed in  claim 1 , wherein the catalyst comprises a basic catalyst. 
     
     
         17 . The process as claimed in  claim 1 , wherein the catalyst comprises a heterogeneous catalyst. 
     
     
         18 . (canceled) 
     
     
         19 . A composition comprising, in each case based on the total weight of the composition,
 (i) 0% and 40% by weight of at least one aromatic compound having at least two amino groups,   (ii) 0% and 35% by weight of at least one aromatic compound having just one amino group,   (iii) 0% to 40% by weight of at least one hydrocarbon compound containing at least one functional group having at least one oxygen atom and no functional group having a nitrogen atom,   (iv) where the proportions by weight within the parts by weight ranges from (i), (ii) and (iii) are selected such that the sum total of the selected proportions by weight from (i), (ii) and (iii) together with the parts by weight of other ingredients add up to 100% by weight.